What actually caused the collapse of Soviet Union and communism in Russia?

On March 17, 1991,
the USSR conducted a referendum, asking people if they would like to
remain in USSR, or go their separate ways. The result is below. The blue
ones said "I want to stay as USSR", and the green ones said "I want to
become an independent country".

Basically,
the 3 Baltic countries wanted to gain independence. They were the
richest, the most industrialized countries in USSR, and they were like
"without USSR, we'd be like Germany!"

In the 5
-stans, i.e., Kazakhstan, Tajikistan, etc., were like "I want to remain
as part of the USSR. Without the USSR, we'd be like Afghanistan!" 95%
voted to stay with USSR.

The 3 central Slavic nations, i.e., Russia, Belarus, and Ukraine, were like around 75% pro-USSR, and 25% pro-independence.

This
should not surprise you. The common people mostly don't like drastic
changes unless their lives have become intolerable. The common people
would most likely be concerned about "how will my job be affected?"
"What's going to happen to my children's kindergarten?" "how will my
pension be affected?" etc. There were no answers to any of these
day-to-day questions.

So what happened? The
people were told "You f*cking brainwashed idots! You don't know what's
good for you!" The Russians, or the Russian elite, i.e., Yeltsin, wanted
out. Economically, Russia had contributed more to the other republics
than getting money back from the other republics, in exchange for the
political influence in other countries. As money got tight, Russia
wanted to drop the burden. Nobody, least of all, the "leader of
democracy", gave a sh*t about "the will of the people".

On Dec. 8th, 1991, 9 months after the USSR Referendum, Yeltsin signed the Belavezha Accords and dissolved USSR with just 2 other republics:

The
story was that Yeltsin got so drunk, that Shushkevich had to grab him
by his arm when he almost fell down from the stairs. Nazarbayev of
Kazakhstan didn't hear about it until 3 days later. He bawled his eyes
out, packed up, went home, and declared independence 8 days later, on December 16th. Dissolution of the Soviet Union

So what happened after the Dissolution?

The
Baltic countries definitely made the economically correct move. All
three of them now have higher GDP per capita than Russia.

The
5 -stans, without Russian injection of cash and technology, mostly did
not fare so well, except Kazakhstan. Ironically, the republic which most
abhor leaving USSR now have a GDP per capita close to Russia, thanks to
the oil and gas exploration.

The original
instigators, i.e., Russia, Ukraine, Belarus, all fared relatively
poorly. All of them took at least 10 years to get back to where they
were before, while the rest of the world has moved on... Ukraine in
particular, 25 years later, is still below their 1990 level.

So
you see, the people were, actually, more correct than the politicians.
They knew that the Baltic countries would be better off, the Central
Asian countries would very likely to be worse off, and the three Slavic
countries, i.e., Russia, Ukraine, and Belarus, would more likely sink
than swim. But there was nothing they could do about it. That's that.
Democracies born out of unbelievably un-democratic political processes.